A syndrome having oliguria, anuria, uremia and so forth as the main sign is called acute renal failure, which began to attract attention during the Second World War because it attacked people which had recovered from traumatic shock due to the air raid on London, and has come to the present state.
Although there are many causes of acute renal failure, it is believed that such failure is mainly caused by hemorrhage due to injury, surgical operation, aortic rupture or the like; diarrhea due to serious enteritis, infection with Salmonella or cholera, or the like; loss of water and/or electrolyte due to burn, continued vomiting, heat stroke or the like; hemolysis due to incompatible blood transfusion, hemoglobinuria or the like; angiopathy such as renal arterial thrombosis; infectious disease such as pneumonia, sepsis, acute hepatitis, pyelonephritis or candidiasis; allergy; anaphylaxis; influence of a carcinostatic agent such as cisplatin; urethral or ureteral obstruction due to prostatic hypertrophy or malignant tumor; urinary obstruction such as ureteral stone; or the like.
Further, a symptom of irreversible decrease in the number of nephrons is called chronic renal failure, and a patient with this failure cannot avoid dialysis with an advance in the symptom, suffering from physical and mental great agony. Additionally, the dialysis of a patient with chronic renal failure generally extends over a long period, so that his expense is also great. Further, it is apparent from the ratio of the number of dialyzers held in Japan to that of the patients necessitating dialysis that the dialyzers must now be worked without intermisission. Therefore, the fact that there are patients with serious acute renal failure who necessitate dialysis temporarily in addition to those with chronic renal failure is significantly problematic.
Under these circumstances, the prevention of the symptom of renal failure from reaching a stage necessitating dialysis has become a great issue. However, there has not been found as yet any means which is effective in the prevention of the symptom of chronic renal failure from reaching such a stage, while the regulation of the body fluid which has lost its balance owing to oliguria or anuria by the administration of a diuretic is conducted as the conservative therapy exclusively for the patients with acute renal failure to secure necessary thermal energy.
It has been a practice in the prior art to use a loop diuretic such as furosemide or ethacrynic acid against acute renal failure. However, such a diuretic causes an adverse reaction such as hearing loss, worsening of diabetes mellitus or hyperuricemia, so that enough care is needed in the administration thereof. Further, it is needless to say that these drugs are ineffective in protecting the kidney positively to normalize the lowered function thereof, because the drugs serve only as diuretic.
Accordingly, it has been expected eagerly to develop a drug which can prevent the worsening of renal failure and which can regulate the body fluid to thereby normalize the function of the kidney.